Infusion pumps are typically used to regulate the delivery of fluids, which may include potentially hazardous drugs, to a patient with a high degree of accuracy. Until a few years ago, in order to prevent "free flow" or "fluid runaway" a roller clamp was moved to a closed position to stop flow through IV tubing without the tubing is removed from an infusion pump. "Free flow" or "fluid runaway" is an undesirable situation where fluid is free to flow rapidly through the IV tubing without regulation by the infusion pump. Such roller clamps are effective in preventing free flow only when they are manually moved to their closed positions, and free flow or fluid runaway may occur if the roller clamp is left in its open position. As a result, automatic free flow prevention systems have recently been provided in which fluid runaway is prevented regardless of whether the pump operator remembers to close a roller or slide clamp.
One preferred free flow prevention system is described in co-assigned U.S. Pat. No. 5,017,192. This system employs a flexible clamp having clamping arms defining a variable width slot. The clamping arms are biased to a closed position in which the lumen of the IV tubing is closed to fluid flow. During operation of the infusion pump, a clamp-opening wedge in the infusion pump spreads the clamping arms to the open position to allow the lumen of the IV tubing to open to fluid flow. This free flow prevention system has been a successful and easy to use method of preventing free flow.
Another approach is described in co-assigned U.S. Pat. No. 4,585,441 wherein an interlock is provided to prevent removal of the IV set unless fluid flow through the tubing is stopped. The pump operator must manually close a clamp to stop fluid flow through the tubing before the infusion pump will permit removal of the IV set.
Co-assigned U.S. patent application Ser. No. 08/070,497, filed Jun. 1, 1993, which is a continuation of Ser. No. 07/690,819, filed Apr. 23, 1991, on Free Flow Prevention System for Infusion Pump, describes a flexible spring clip that is particularly adapted for use with a pumping cassette of the type described in co-assigned U.S. Pat. Nos. 4,236,880; 4,277,226; 4,322,201; 4,382,753; 4,391,600; and 4,410,322.
Other approaches include employing slide clamps to prevent or reduce the risk of removing the IV set without closing a clamp. U.S. Pat. Nos. 4,586,691; 4,689,043 and 4,818,190 describe employing slide clamps to prevent fluid runaway during removal of IV sets from infusion pumps.
U.S. Pat. No. 4,944,485 describes a clamp having a pair of clamping members pivotally hinged together and biased to clamp a segment of IV tubing. That clamp also includes a latch for latching the clamp in an open position.